The purpose of this project is to evaluate the overall and age-specific incidence rates of various chronic pain syndromes by developing a statistical technique to estimate incidence rates from age of onset data. The technique developed uses available estimates of age of onset data for headache and approximates incidence rates by superimposing the age of onset rates onto the age distribution of the given population. The incidence rates of disabling and/or severe headache were evaluated with data obtained from a Midwest non-clinical population survey. The validity of this procedure was evaluated by comparing the results with the incidence of disabling headache estimated from the British Second National Study of Morbidity Statistics. A report on this work has been prepared and will be submitted for publication.